Base metal alloy



Patented Feb. 4, 1941 UNITED STATES BASE METAL ALLOY Charles J. Koebel, Detroit, Mich., assignor to Koebel Diamond Tool 00., Detroit, Mich., a corporation of Michigan No Drawing. Original application January 12,

1932, Serial No. 586,238. Divided an! this application November 22, 1939, Serial No. 305,603

1 Claim.

This invention relates generally to alloys and has more particularly reference to alloys used for the purpose of setting diamonds, carbonados or the like. The present application is a division of application Ser. No. 586,238, filed January 12, 1932.

Diamonds are now being used to a very great extent in the industrial arts, examples of such use being: as dressing tools for grinding wheels; as core bits for rock drilling; as saw teeth; and as dies for drawing wire. Manifestly their use for such purposes, as have been indicated above, imposes strains and stresses of considerable magnitude upon the diamonds and their mountings. Unless the diamond is held very firmly in its mounting, it may work loose and become lost or, if not lost, it will quickly destroy its own setting and will become useless as a tool. It is the practice now to use relatively large stones and to reset them when they work loose. Repeated resettings however, especially if heat be used, have a very deleterious effect upon the diamond, and it is therefore not always possible to reset a diamond as it may have become injured or its skin may have been destroyed or penetrated, by adjacently mounted diamonds or otherwise, to such an extent that it is no longer serviceable in the task for which it is intended.

It is the main object and feature of this invention to produce an alloy which possesses such characteristics that when subjected to heat at a point below the critical point at which the desirable qualities of the diamond are impaired, said alloy exhibits the property of wetting the diamond coupled with a lack of avidity for the carbon of the diamond, and when thereafter cooled or closely adhering to it.

The critical point above mentioned appears to be in most cases in the neighborhood of 1380 degrees centigrade, although it varies with different stones. Excellent results have been obtained by using a temperature between 1245 and 1260 degrees centigrade.

The following formula of an alloy, successfully used, is given:

Per cent Molybdenum 40 Coba 20 Copper 40 The proportions given are approximate and are by weight and not by volume. The materials of which the alloy is composed are reduced to powder form and thoroughly mixed, a slight amount of parafline being added, before the diamond is imbedded therein. Molybdenum is chosen because, apparently, it imparts a hardness of high degree to the finished setting. The function of the cobalt appears to be that of rendering the alloy wettable with respect to the diamond. The copper seems to prevent the alloy from robbing the diamond of carbon.

The diamond or diamonds are imbedded in a mass of the comminuted alloy of the character described, after which said alloy is subjected to pressure so as to shape it. The pressure used may be from thirty to forty tons to the square inch, and causes the mass to be shaped into a body capable of substantially maintaining its form when pressure is thereafter removed. The shaped body is then introduced into a. furnace and heated to a temperature below the critical point above mentioned, say 1245 degrees centigr-ade, said furnace being devoid of oxygen, after which the mass is cooled in a chamber also devoid of oxygen. If desired, there maybe a preliminary heating of the shaped body in another furnace, also devoid of oxygen, and good results have been obtained with a preliminary heating of 650 degrees centigrade and a final heating of 1225 degrees centigrade.

During the heating, the body has shrunk but slightly but has become a coherent solid sintered mass in which the diamonds are imbedded in the same relative position they originally occupied, and it would therefore seem that the effective coefiicient of expansion of the alloy approximates that of the diamond.

I claim:

As a new article of manufacture, a setting for diamonds composed of an alloy including molybdenum approximately forty percent, copper approximately forty percent, and cobalt approximately twenty percent.

CHARLES J. KOEBEL. 

